Control apparatus



T. A. WETZEL CONTROL APPARATUS Dec. 29, 1942.

Filed June 17, 1938 2 Sheets-Sheet 1 7 flverzforz 22 600 07? K. We 2376 2' Q lam W $222241 I Uzi Mu 1942- 'r. A. WETZEL CONTROL APPARATUS 2 Sheets-Sheet 2 Filed June 17, 1938 Patented Dec. 29, 1942 UNITED STATES PATENT OFFICE CONTROL APPARATUS 'Theodore A. Wetzel, Milwaukee, Wis., assignor to Milwaukee Gas Specialty Company, Milwaukee, Wis., a corporation of Wisconsin Application June 1'7, 1938, Serial No. 214,367

12 Claims. (Cl. 158-4171) in which the main burner of a space heater or other heater is controlled by the pilot lighter, it is to be understood that the invention is not limited in these respects to the particular embodiments selected for illustration. For example, the invention may be applied to a reactor, a magnetic valve, a motorized valve, or other device the operation of which will depend on the shifting of the alternating current flux by virtue of the direct current magnetization by means of the thermocouple, and the controlled means may be any burner or other means adapted to be controlled by the device the operation of which is controlled by the shifting flux.

On of the main objects of the invention is to provide a control apparatus adapted for utilizing the thermoelectric current produced by a thermocouple for shifting the magnetic fiuxfrom one magnetic circuit to another toprovide the desired control.

It is also an object of the invention to provide a control apparatus in which a current amply diagrammatic view howing another embodiment of the invention.

With reference now to the drawings, in the particular embodiment of the invention illustrated in Figure 1, l designates a main burner which may be the main burner of a room or other space heater, an oven burner, or any burner or other device which it is desired to control by the control apparatus of the present invention.

The burner In, which has burner openings indicated at H, is supplied with gaseous or other suitable fuel from a fuel supply conduit l2 by way of a nozzle pipe I3 which delivers the gaseous fuel into the mixing chamber H at the outer end of the feed pipe l5. Air may be admitted to the mixing chamber I4 in th usual or any suitable or preferred manner, and the opposite end of the feed pipev is connected to the burner ID for feeding the mixture of air and gaseous fuel theresufficient to operate and maintain the control device in operative position may be controlled by a relatively weak thermoelectric current in a simple, inexpensive and improved manner and, if desired, without moving parts in the control apparatus, although moving parts may be employed within the broader aspects of the invention, as will hereinafter appear.

Other advantages and adaptations of the invention will be apparent from the following de tailed description. taken in connection with the accompanying drawings, in which:

Figures 1 and 2 are more or less schematic or diagrammatic views showing two forms of control apparatus and controlled systems embodying the present invention;

Figure 3 illustrates the magnetic structure and windings of tion;

Figure 4'is a schematic or diagrammatic view showing another system embodying the invention;

Figure 5 is a view similar to Figure 3, illustrating the magnetic structure and windings of another embodiment of the invention; and

Figure 6 is a fragmentary and more or less another embodiment of the -lnvenv to. The heater may have an enclosing wall (not shown), and the fuel supply conduit I2 is provided with a fuel control valve indicated at It. A pilot lighter I8 is provided in appropriate proximity to the burner l0. Fuel is supplied to the pilot lighter l8 by a tube l9 which may lead from the fuel supply conduit l2 of from any other suitable or preferred source of fuel.

The control apparatus shown in Figure 1 comprises a magnetic core 20 of laminated or other suitable form. The particular core 20 shown in this figure has opposite side legs 2|; 2|, end legs 22, 23, and a pair of shunt legs 24, 24 connecting the side legs 2|, 2| intermediate the end legs 22 an 23.

An alternating current primary wind ng 25 is wound around the end leg 22 and connected, for example, by a transformer 26 or otherwise as desired to an alternating current circuit 21. The circuit 21 may be an alternating current lighting circuit or any other alternating current circuit supplied by a suitable source of alternat ng current (not shown). Where the apparatus is used for controlling a space heater as above described, a thermostat 28 and any other control or controls shown schematically at 29 may be connected in series in the circuit 30 which includes the alternating current primary-winding 25. The thermostat 28 may be opened and closed in accordance with the temperature of the room heated by the heater, where the heater is a room heater, or the thermostat 28 may be arranged to be opened and closed in accordance with the temperature of the water in the tank associated with th burner In,

where the heater is a water heater, or otherwise as desired. The control 29 may be a limit control cent to this flame to be subject to the heat there-,

of. The thermocouple members 33 and 34 are formed of d ssimilar metals, such as, for example,

' position. This shifting of the magnetic flux set up by the alternating current winding 25 from the v.motor path to the shuntspath is produced by the iron and Constantin, Chromeliand Copel,.'

Chromel and Constantin.Chromel and Al discontinuance. or drop indirect current flux density produced in the shunt legs 24 by the 1 ther'mo-electr'ic current produced by the thermoumel, or any of numerous othercombinations.

The other two thermal junctions 39 and 40 of the thermocouple members-33 and 34'are connected by conductors 4| and 43 to a pair of direct current windings 42 wound around the shunt legs 24, 24

of the core and connected in series circuit relation in the direct currentcircuit. 43 which includes the thermocouple 32.

The leg 23 of the core 20 has the stator .45 of I an alternating current motor formed integral therewith. The stator 45"comprises pole pieces couple upon extinguishment of the pilot lighter. As a result, the torque or turning movement imparted to the rotor 41 is materially diminished and the valve member 52 is actuated to closed =;;;position-for example, .by means of a spring 62 48. with a gap therebetween forthe rotor 41.

For prod c ng the desired rotationfthe rotor 41' is preferably of squirrel cage or othersuitable form. and the stator pole pieces are provided with shad ng coils or other su tablemeans indicated at 48. The rotor 41 of the motor ism'ounted between the stator poles 46 for rotation about the axis of the rotor shaft 50. and is connected at 5| to actuate the valve member 52 within the valve hous ng of the fuel control'valve H; to open" or by. other means as desi'red.to shut off the supply'of fuel to the burner l0.

. When the pilotlighter I8 is reignited, the magnetic fiux set up in the .shunt legs24 by the thermo-electric current produced by the thermocouple diver'tsthe magnetic flux set up by the alternating current winding 25 from the shunt path or shunt legs to the motor path, and the motor is operated thereby to actuate the valve member 52 to open position. Opening of the valve member 52.sets up a supply of fuel to the burner l0, where it issues from the ports, and is i nited by the. l ghter flame 36.

In the embodiment of the invention illustrated in Figure 2, the magnetic core 20' of the control apparatus has opposite side legs 10, I0,

' end legs 1|, 12, less 13, 13 connecting the side leg 12, instead of being interrupted to,form thev "stator of a motor as in the preced ng embodienergizat on of the windings 42 the ma netic flux set up in the core 20 thereby threads through the shunt legs 24 and throu h the core portions 56 generally. as ind cated diagramatically by the dot and dash l ne 51.

The alternating current primary wind ng 25,

being energized. sets up magnetic flux in the core- 20. This ma gnetic flux set up bythe alternating current w nding 25 is d verted from the s unt le s 24 of the core 20 so lon as the lot l ghter I8 is li ted by the magnetic flux set up by the direct current energ zation of the w nd ngs 42. As a result. the ma netic flux set up by the alterna in current windin 25 comnl test e lon path throu h the core legs 2 22 and 23 and through the rotor of the haded pol motor. substantially as indica ed d agrammat cal y bv the dot and dash l ne'58. The rotor is tu ned in a direction to actuate the valve member 52 to open position and to hold same open by the resulting toroue so long as the coil 25 is energized and the mits a supply of fuel to the burner 84.

legs 10, 10 intermediate the end legs 1|, 12, and a leg" connecting the legs 13, 13 intermediate the side legs 10. 18. I

The alternating current pr mary wind ng 15' is woundv around the end leg 1| and connected by input leads 15 to a suitable source of alternatingcurrentinot shown). The oppos te end merit ofthe invent on, is continuous and has a seoond'arywi'nd ng 18 wound around the same. The winding 18 is'conn'ected in series circu t relation in an output circu t 19 which. in the illustrated embod ment. includes in series circuit relat on the coil of an elect ic valve 8". a t ermostat BL and another control dev ce 82. wh ch latter control device maybe a l mit cont ol or other control device. Theco ntrol device 29 of Fi ure lmay likewise. as already'explained. be a lim t control, for shutting on" the fuel supply to the bu ner at predetermined temperatu es.

-The electric valve is placed in the fuel supply conduit' 83 for supplying gaseous or other suitable fuel to the burner 84 by way of a nozzle pipe 85, mixing chamber 86, and feed pi e 81 connected to the burner 84. The burner has burner openings 88. The electric valv 80 is connected into the output circuit 19 of the control apparatus, and the valve operates to open position when it is energized and thereby per- When the valve 80 is deenergized it closes and shuts off the fuel supply to the burner 84. Valves of this sort are well known in the art and will not be described in detail here.

A pilot lighter is provided in appropriate proximity to the burner 84. Fuel is supplied to the pilot lighter 90 by a tube 9| which may lead from the fuel supply conduit 83, or from any other suitable or preferred source of fuel. The thermocouple 92, which in this case is of the type disclosed and claimed in the copending application of Oscar J. Leins, Serial No. 4,741, filed February 4, 1935, comprises an outer metallic tubular thermocouple member 93 and an inner thermocouple member of dissimilar metal, as hereinbefore described, disposed within the tubular thermocouple member and joined to said tubular thermocouple member to form a thermal junction at 95. A tubular conductor 96 forming one of the thermocouple leads is connected'to the outer tubular thermocouple member 93 at 9! to form a second thermal junction, and the internally; disposed conductor extending through the conductor 96 isconnected to the inner thermocouple member 94 at 99 to forms. third and enclosed thermal junction forthe thermocouple.-

jThethermocouple leads 96 and 98 are" connected to a direct'current winding I02 wound around the leg I4 of the core20.

In operation of the embodiment of the invenrent flux from the leg I2 to the shunt path it produced upon extinguishment of the pilot lighter by the accompanying discontinuance of direct current flux or drop in direct current flux density in the shunt path- As a result, the winding II and its circuit I9 are deenergized and th valve 66 is actuated to closed position-for example,

by a spring or otherwise as desiredto shut oi! ing current flux set up by the winding 15 from the shunt. pathto the path I06 including the leg I I2 and the output circuit I9 is energized to open the valve '80 providing-circuit I9 is completed through thermostat BI and auxiliary controls 82.

I Opening of the valve 80 sets up a supply of fuel tion shown in Figure 2, and assuming that the I pilot lighter 90 is lighted, the pilot flame at the thermocouple junction 95 sets up "and maintains, so long as the pilot lighter is lighted, a direct and particularly a thermo-electric current through the circuit including the conductors 96 and 98 and the direct current'winding I02. The winding I02 is thus energized and the magnetic flux set up in the core 20 thereby threads through the core legs 10,. I3 and I4 generally, as indicated diagrammatically by thedot and dash lines. l05. What might betermed the shunt portion of the I magnetic core 20 in this embodiment or the invention is surrounded or'enclosed by the main portion of the'core which is thus of the shell type; I

The alternating current primary winding 15 being energized sets up magnetic flux in th core 20. So long a the vpilot flame 90 is lighted, the greater portion of this magnetic flux set up by the alternating current winding I5 is diverted.

from the shunt legs'I3 of the c0re'20, bythe magnetic fluxset up by the direct current energization of the single winding I02. magnetic flux set up by the alternating current winding completes the long path through the core legs II, I0, I0, and I2 as indicated diagram- The matically by the dot and dash line I05. magnetic flux passing through the leg I2 of the core produces a current in the secondary winding I8, thereby energizing the circuit I9 which includesthe coil tithe electric valve. 80. This. energization of the coil of the valve 60opens this As a result, the I the long'path I06 including the leg I2, takes the path of least resistance, i. e., the path through the shunt legs I3 as shown by dot and dash lines I08, or through at least one of these legs I3.

It is understood, however, that the small amount of flux remaining at this time in leg I2 is insuiiicient to maintain electric valve 80 in its open position. This shifting of the alternating cur- Winding I02.

to the burner 04 where it issues from the ports 83 andis ignited by the lighter flame I00.

Figure 3 shows a magnetic core structure 20" similar to the core structure shown in Figure 2 and with the windings similarly arranged thereon, like parts being designated by primed reference characters corresponding with the reference characters in Figure 2. In this embodiment, however, an extra short circuited coil orring H0 is wound on the leg I4 under the direct current Said coil or ring may be in the form of washers placed beside the coil I02. This short circuited coil or ring'operates to maintain a constant-direct current flux, when the direct current winding I02 is energized by resisting the bucking action of the alternating current flux when it tends to neutralize the direct current flux; This also minimizes. any-induced alternating current ripple in the direct current electric circuit. Another winding may be wound on the same leg as the direct currentwinding I02 for the purpose of canceling out any direct current magnetization in order to secure a reverse action control.

The embodiment of the invention illustrated in Figure 4 is similar'to the embodiment illustrated in Figure 2. except that in this case the circuit 19" of the secondary output coil 10 has a time clock II2 controlling a time switch I I3 for opening and closing the circuit 19" and thereby opening and closing the valve 80" at. predetermined time intervals to provide a timed control for the burner V The clock I'I2 is'shown as an electric clock connected by leads H4 to the'leads 16" for the alternating current primary winding 15'. The leads "I6" are'shown as connected to the alternating current supply circuit II5 by a transformer H6, and other parts which are similar to parts shown in Figure 2 are designated by doubleprimed reference characters corresponding with the reference characters in Figure 2.

In the embodiment of the invention shown in Figure 5 the core structure I has side legs I3I, end legs I32, I33, and two legs I34 and I35 connecting the side legs I3I between the end legs. The alternating current primary winding I36 is wound around the leg I34 and connected by input leads I31 to a suitable source of alternating cur rent. The secondary or output winding 533 is wound around the end leg I32 and connected to the controlled or output circuit I39. The direct current winding I40 is wound around the end leg I33 and is connected by leads I4I to the thermocouple I42 as described in connection with the preceding embodiments of the invention. The thermocouple I42 is placed with the junction I44 thereof in the pilot flame I45 of the pilot lighter I46 or in appropriate proximity thereto. A shortcircuited band or coil I48 is preferably wound on the leg I33 under the direct or thermoelectric current winding I40 for the purposes described in connection with the short-circuited band or winding H in Figure 3.

With the alternating current primary winding I38 energized by the alternating current circuit, alternating current flux is set up generally as indicated by the lines I50, the magnetic lines of force passing through the end leg I32 at this time producing a current in the secondary coil I38, but this current is insufilcient to operate the desired devices or produce the desired control. However, when the pilot flame I45 is burning the thermoelectric current set up thereby in the coil I40 produces direct current flux generally as indicated by the dot and dash line I52. This direct current flux diverts the alternating current flux from the leg I35 through the end leg I32 along the upper dot and dash line I50 and, as a result, the current in the secondary coil I38 is increased sufficiently to provide the desired control or operation of the devices in the circuit I39.

The embodiment of the invention shown in Figure 5 produces the controlling operation by a current differential, but the structure may be modifled to produce either a secondary output current or no secondary output current, depending upon the path of the flux as controlled by the direct or thermoelectric current. For example, by making the lower flux path I50 sufiiciently shorter than the upper flux path I50 the entire or substantially the entire alternating current flux may follow only the lower path I50 when the direct current coil I40 is deenergized. Then, upon energization of the coil I40, the direct current flux produced thereby will shift the alternating current flux from the lower flux path I to the upper flux path I50 to provide the desired operation or control.

The structure shownv in. Figure 5 permits of a shorter flux path for the working alternating current flux and also permits a suitable form for the direct current coil in that it allows a long winding axiall and thus provides a minimum length 01' mean turns to secure maximum ampere turns.

The magnetic path to the right of the line a--a in Figure 2, as well as the corresponding'magnetic paths in the other figures, may consist of a relay, solenoid, motor, or any other device the operation of which will depend on the shifting of the alternating current flux by virtue ofthe direct current magnetization by means of the thermocouple as herein described.

In Figure 6 for example, the magnetic path to the right of the line (1-11 is in the form of a relay having an armature I15 pivoted at I16. The magnetic structure I11 and coil arrangement to the left of the line a-a may correspond with the magnetic structure and coil arrangement to the left of the line M in Figure 2 or with the corresponding portion of the magnetic structure and coil arrangement of the other figures, or may be of other desired form.

Thearmature I15 carries a contact I18 connected to one side of a secondary winding I18 of a transformer I80. The primary winding I8I of the transformer I80 is connected by leads I82 to a suitable alternating current supply circuit or source of alternating current supply. The opposite side of the winding I18 is connected by a lead I83 to one side of the output circuit,.while the other side of the output circuit is connected by a lead I84 to a contact I85, for example through a bracket I88 secured upon a suitable insulating support I81. The contact I85 is in the form of a contact screw having threaded engagement in the bracket I88 for adjustment toward and away from the contact I18. The output circuit to the right of the line bb may be as shown to the right of the line bb in Figure 2, or it may be of any other character desired.

The upper end oi. the armature I15 and the cooperating portion of the magnetic structure I11 are preferably provided with shading coils I for the purpose of providing a continuous pull when the armature is attracted to position against the magnetic structure I11 as shown in dotted lines at I92. These coils or other suitable shading means prevent chattering oi the armature in its movement to the dotted line position I92.

In operation of the embodiment of the invention shown in Figure 6, the thermo-electric current set up when the pilot lighter is lighted as shown in the other figures shifts the alternating current magnetic flux through the illustrated portion of the magnetic structure I11 and armature I18 is attracted to its dotted line position I82, in which position the contact I18 carried by the armature is engaged with the contact I and closes the output circuit I83, I84. This circuit is thereupon fed with alternating current from the source of alternating current supply through the transformer I80. The current set up in the output circuit I83, I84 is thus not confined to that produced by the alternating current magnetic flux but may be any desired independent current, the circuit I83, I84 being merely controlled by the action of the relay which in turn is controlled by the alternating current magnetic flux, and this alternating current magnetic flux in turn is controlled by the thermo-electric means. The output circuit I83, I84 may of course be a direct current circuit under the control of the relay controlled by the alternating current magnetic flux, which in turn is con trolled by the thermo-electric means.

When the pilot lighter is extinguished or the thermo-electric circuit otherwise becomes deenergized, the alternating current magnetic flux in the illustrated portion of the magnetic structure dimishes sufficiently so that the armature I15 cases to be held in the dotted line position and swings by gravity to its full line position,'opening the output circuit at the contacts I18, I85. If desired, spring means may be employed in addition to or in lieu of the off-center pivoting of the armature I15 and carrier for contact I18 for separating the contact I18 from thecontact I85 when'the alternating current magnetic flux in the illustratedj portion'of the magnetic structure is diminished o'r discontinued.

I do not intend to be limited to the precise details shown or described.

1. In combination, aburner, a pilot-lighter therefor, a control valve for said burner, a magnetic structure having a first leg for an alternating current winding and a second leg, means on said second leg and controlled by the magnetic lines of force therein for controlling said valve, a shunt path between said first and second legs through which the alternating current flux normally is adapted to pass, a thermocouple in proximity to said pilot lighter, and a direct current winding connected to said thermocouple and operative upon energization of said thermocouple to produce a direct current flux in said magnetic structure for diverting the alternating current iiux from said shunt path to said second leg.

2. In combination, a magnetic structure having a first leg for an alternating current primary winding and a second leg, an alternating current primary winding on said first leg, 8. secondary winding on said second leg, an output circuit connected to said secondary winding, a burner, a pilot lighter therefor, a control valve for said burner, means in said secondary output circuit for controlling said valve, an auxiliary control switch in said circuit, a shunt path between the first and second legs of said magnetic structure through WhlUh the alternating current flux normally is adapted to pass, a thermocouple in,proximity to the pilot lighter, and a direct current winding connected to said thermocouple and operative upon energization of said thermocouple to produce a direct current flux in said magnetic structure for diverting the alternating current flux from said shunt path to said second leg to energize said secondary winding and said output circuit.

3. In combination, a burner, a pilot lighter therefor, a control valve for said burner, a magnetic structure having a first leg for an alternating current winding and a second leg, means on said second leg and controlled by the magnetic lines of force therein for controlling said valve, said magnetic structure comprising a shunt path through which the alternating current flux normally is adapted to pass and to be thereby diverted from said second leg, a thermocouple in proximity to said pilot lighter, and a direct current winding connected to said thermocouple and operative upon energization of said thermocouple to produce a direct current flux in saidshunt path effective for diverting the alternating current flux from said shunt path to said second leg.

4. In combination, a burner, ignition means therefor, a control valve for said burner yieldingly urged closed, a magnetic structure'having a first leg for an alternating current winding and a second leg, said magnetic structure comprising a shunt path through which the alternating current flux normally is adapted to pass and to be thereby diverted from said second leg, a thermocouple heated by said ignition means, a direct current winding connected to said thermocouple and operative upon energization, from said thermocouple to produce a direct current flux in said shunt path effective for diverting the alternating current flux from said shunt path to said second leg, a unidirectional motor connected to said valve for opening it when said motor is effectively energized, and supplementary means for effectively energizing said motor responsive to energization of said direct current winding and for deenergizing said motor effective to permit closing of said valve responsive to deenergization of said direct current winding.

5. In combination, a burner, a pilot lighter for said burner, control means for said burner, a

magnetic structure having a first flux path for an alternating current winding and a second flux path, means in said second flux path and controlled by the magnetic lines of force therein for controlling said control means, said magnetic structure comprising a shunt path through which the alternating current flux normally is adapted to pass and thereby to be diverted from said second flux path, a thermocouple subject to heat of said pilot light, and a direct current winding connected in circuit with said thermocouple and operative upon energization of the thermocouple to produce a direct current flux in said shunt path for diverting the alternating current flux from said shunt path to said second flux path.

6. In combination, a burner, a fuel supply pipe leading to said burner, ignition means for said burner, control means for said burner yieldingly urgedv to position to shut off the flow of fuel to said burner, a magnetic structure having a first flux path for an alternating current winding and a second flux path, said magnetic structure comprising a shunt path through which the alternating current flux normally is adapted to pass and thereby to be diverted from said second flux path, a thermocouple in position to be heated by said ignition means, a direct current winding connected in circuit with said thermocouple and operative upon eneiglzation of said thermocouple to produce a direct current flux in said shunt path effective to divert the alternating current flux from said shunt path to said second flux path, a motor connected to said control means for operating said control means to position to set up and maintain a flow of fuel to said burner when said motor is energized and means for energizlng said motor responsive to energization of said direct current winding and for deenergizing said motor to permit operation of said control means to position to shut off the supply of fuel to said burner responsive to deenergization of said direct current winding.

7. In combination, a burner, a pilot lighter therefor, an electroresponsive control valve for said burner, a magnetic structure having a first leg for an alternating current winding and a second leg, a winding on said second leg and connected in circuit with said electroresponsive valve for energizing said valve by magnetic lines of force in said second leg, said magnetic structure comprising a shunt path through which the alternating current flux is adapted to pass and to be thereby diverted from said second leg, a ther mocouple in proximity to said pilot lighter, and a direct current winding connected to said thermocouple and operative upon energizatlon of said thermocouple to produce a direct current flux in said shunt path effective for diverting the alternating current flux from said shunt path to said second ice.

8. In combination, a burner, a pilot lighter therefor, an electroresponsive control valve for said burner, a magnetic structure having a first leg for an alternating current winding and a second leg, a winding on said second leg and connected in circuit with said electroresponsive valve for energizing said valve by magnetic lines of force in said second leg, said magnetic structure comprising a shunt path through which the alternating current flux is adapted to pass and to be thereby diverted from said second leg, a thermocouple in proximity to said pilot lighter, a direct current winding connected to said thermocouple and operative upon energization of said thermocouple to produce a direct current flux in said shunt path effective for diverting the alternating current flux from said shunt path to said second leg, and means in circuit with the winding on said second leg for providing an additional control for said valve.

9. In combination, a burner, a pilot lighter therefor, an electroresponsive control valve for said burner, a magnetic structure having a first leg for an alternating current winding and a second leg, a winding on said second leg and connected in circuit with said electroresponsive valve for energizing said valve by magnetic lines of force in said second leg, said magnetic structure comprising a shunt path through which the al ternating current flux is adapted to pass and to be thereby diverted from said second leg, at thermocouple in proximity to said pilot lighter, a direct current winding connected to said thermocouple and operative upon energization of said thermocouple to produce a direct current flux in said shunt path effective for diverting the alter nating current flux from said shunt path to said second leg, and time controlled switch means connected in circuit with the winding on said second leg to provide a time control for said valve.

10. In combination, a burner, control means for said burner, a magnetic structure having a first portion for a first winding and a second portion,

means on said second portion and controlled by the magnetic lines of force therein for controlling the control means for said burner, said magnetic structure comprising a shunt portion through which the flux set up by said first winding is adapted to pass and to be thereby diverted from the second portion of said magnetic structure, a thermocouple adapted to be subjected to the heat of a flame, and a second winding connected in circuit with said thermocouple and operative upon energization of the thermocouple to produce in the shunt portion of said magnetic structure a flux for diverting the first-mentioned flux from the shunt portion of said magnetic structure to the second portion of said structure.

11. In combination, a burner, control means for said burner, a magnetic structure having a first portion for a first winding and a second portion, said magnetic structure comprising a shunt portion through which the flux set up by said first winding is adapted to pass and to be thereby diverted from the second portion of said magnetic structure, a thermocouple adapted to be subjected to the heat of a flame, a second winding connected in circuit with said thermocouple and operative upon energization of the thermocouple to produce in the shunt portion of said magnetic structure a flux for diverting the first-mentioned flux from the shunt portion of said magnetic structure to the second portion of said structure, and a motor connected to said control means for actuating same when the motor is effectively energlzed and responsive to the flux diverted to the second portion of said magnetic structure by the energization of said thermocouple.

12. In combination, a magnetic structure having a first portion for a first winding and a second portion, said magnetic structure comprising a shunt portion through which the flux is set up by said first winding is adapted to pass and to be diverted from the second portion of said magnetic structure, a thermoelectric generator adapted to be subjected to the heat of a flame, a sec ond winding connected in circuit with said thermoelectric generator and operative upon energl-- zation of the thermoelectric generator to produce in the shunt portion of said magnetic structure a flux for diverting the first-mentioned flux from the shunt portion of said magnetic structure to the second portion of said structure, and means responsive to the flux diverted to the second portion of said magnetic structure by the energize.- tion of said thermoelectric generator.

THEODORE A. WETZEL. 

